Gut microbiota in autoimmunity: potential for clinical applications

Glaucoma and the Human Microbiome

PURPOSE OF REVIEW

To explore a view of the human microbiome as an interconnected, functional, dynamic system that may be linked to the pathogenesis and progression of glaucoma.

METHODS

A literature review was undertaken that included publications from 1966 to 2023.

RESULTS

Bacterial lipopolysaccharides (LPS) activate toll-like receptors (TLR) and mediate the human immune response. The LPS-TLR4 pathway is a potential avenue for the ocular, gut, and oral microbiomes to interface and/or influence ocular disease. Studies of gut dysbiosis have shown that alterations in the healthy microbiota can predispose the host to immune-mediated inflammatory and neurodegenerative conditions, while oral and ocular surface dysbiosis has been correlated with glaucoma. While developmental exposure to commensal microflora has shown to be necessary for the autoimmune and neurodegenerative responses to elevated intraocular pressure to take place, commensal bacterial products like short-chain fatty acids have regulatory effects protective against glaucoma.

SUMMARY

Alterations to human microbiotas have been associated with changes in intestinal permeability, gene regulation, immune cell differentiation, and neural functioning, which may predispose the host to glaucoma. Select microbes have been highlighted for their potential contributions to glaucoma disease progression or protection, raising the potential for microbiota-based treatment modalities. Current topical glaucoma treatments may disrupt the ocular surface microbiota, potentially having ramifications on host health. Further study of the relationships between human microbiome and glaucoma is needed.

Molecular mechanisms of gut microbiota in diabetic nephropathy

Diabetic nephropathy is a common complication of diabetes and a considerable contributor to end-stage renal disease. Evidence indicates that glucose dysregulation and lipid metabolism comprise a pivotal pathogenic mechanism in diabetic nephropathy. However, current treatment outcomes are limited, as they only provide symptomatic relief without preventing disease progression. The gut microbiota is a group of microorganisms that inhabit the human intestinal tract and play a crucial role in maintaining host energy balance, metabolism, and immune activity. Patients with diabetic nephropathy exhibit altered gut microbiota, suggesting its potential involvement in the onset and progression of the disease. However, how a perturbed microbiota induces and promotes diabetic nephropathy remains unelucidated. This article summarizes the evidence of the impact of gut microbiota on the progression of diabetic nephropathy, with a particular focus on the molecular mechanisms involved, aiming to provide new insights into the treatment of diabetic nephropathy.

"Does the Gut microbiome influence disc health and disease?-the interplay between dysbiosis, pathobionts, and disc inflammation: a Pilot Study"

BACKGROUND CONTEXT

Gut microbiome alterations resulting in inflammatory responses have been implicated in many distant effects on different organs. However, its influence on disc health is still not fully investigated.

PURPOSE

Our objective was to document the gut biome in healthy volunteers and patients with disc degeneration and to understand the role of gut dysbiosis on human disc health.

STUDY DESIGN

Experimental case-control study.

PATIENT SAMPLE

We included 40 patients with disc degeneration (DG) and 20 healthy volunteers (HV). HV comprised of age groups 30 to 60 years with no known record of back pain and no clinical comorbidities, with normal MRI. Diseased group (DG) were patients in the same age group undergoing surgery for disc disease (disc herniation-25; discogenic stenosis-15) and without instability (with Modic-20; and non-Modic-20).

OUTCOME MEASURES

N/A.

METHODS

We analyzed 16S V3-V4 rDNA gut metagenome from 20 healthy volunteers (HV) and compared the top signature genera from 40 patients with disc degeneration (DG) across Modic and non-Modic groups. Norgen Stool DNA Kit was used for DNA extraction from ∼200 mg of each faecal sample collected using the Norgen Stool Collection Kit.16S V3-V4 rDNA amplicons were generated with universal bacterial primers 341F and 806R and amplified with Q5 High-Fidelity DNA Polymerase. Libraries were sequenced with 250×2 PE to an average of 0.1 million raw reads per sample (Illumina Novaseq 6000). Demultiplexed raw data was assessed with FastQC, and adapter trimmed reads >Q30 reads were processed in the QIME2 pipeline. Serum C-reactive protein (CRP) was measured by the immunoturbimetry method and Fatty acid-binding protein 5 (FABP5) was measured in albumin-globulin-depleted plasma through global proteome analysis.

RESULTS

We observed significant gut dysbiosis between HV and DG and also between the Modic and non-Modic groups. In the Modic group, commensals Bifidobacterium and Ruminococcus were significantly depleted, while pathobionts Streptococcus, Prevotella, and Butryvibrio were enriched. Firmicutes/Bacteroidetes ratio was decreased in DG (Modic-0.62, non-Modic-0.43) compared to HV (0.70). Bacteria-producing beneficial short-chain fatty acids were also depleted in DG. Elevated serum CRP and increased FABP5 were observed in DG.

CONCLUSION

The study revealed gut dysbiosis, an altered Firmicutes/Bacteroidetes ratio, reduced SCFA-producing bacteria, and increased systemic and local inflammation in association with disc disease, especially in Modic changes. The findings have considerable importance for our understanding and prevention of disc degeneration.

Indole-3-acetic acid ameliorates dextran sulfate sodium-induced colitis via the ERK signaling pathway

Microbiota-derived catabolism of nutrients is closely related to ulcerative colitis (UC). The level of indole-3-acetic acid (IAA), a microbiota-dependent metabolite of tryptophan, was decreased significantly in the feces of UC patients. Thus supplementation with IAA could be a potential therapeutic method for ameliorating colitis. In this work, the protective effect of supplementation with IAA on dextran sulfate sodium (DSS)-induced colitis was evaluated, and the underlying mechanism was elucidated. The results indicated that the administration of IAA significantly relieved DSS-induced weight loss, reduced the disease activity index (DAI), restored colon length, alleviated intestinal injury, and improved the intestinal tight junction barrier. Furthermore, IAA inhibited intestinal inflammation by reducing the expression of proinflammatory cytokines and promoting the production of IL-10 and TGF-β1. In addition, the ERK signaling pathway is an important mediator of various physiological processes including inflammatory responses and is closely associated with the expression of IL-10. Notably, IAA treatment induced the activation of extracellular signal-regulated kinase (ERK), which is involved in the progression of colitis, while the ERK inhibitor U0126 attenuated the beneficial effects of IAA. In summary, IAA could attenuate the clinical symptoms of colitis, and the ERK signaling pathway was involved in the underlying mechanism. Supplementation with IAA could be a potential option for preventing or ameliorating UC.

Bacteroidaceae, Bacteroides, and Veillonella: emerging protectors against Graves' disease

Background

Graves' disease (GD) is the most common cause of hyperthyroidism, and its pathogenesis remains incompletely elucidated. Numerous studies have implicated the gut microbiota in the development of thyroid disorders. This study employs Mendelian randomization analysis to investigate the characteristics of gut microbiota in GD patients, aiming to offer novel insights into the etiology and treatment of Graves' disease.

Methods

Two-sample Mendelian randomization (MR) analysis was employed to assess the causal relationship between Graves' disease and the gut microbiota composition. Gut microbiota data were sourced from the international consortium MiBioGen, while Graves' disease data were obtained from FINNGEN. Eligible single nucleotide polymorphisms (SNPs) were selected as instrumental variables. Multiple analysis methods, including inverse variance-weighted (IVW), MR-Egger regression, weighted median, weighted mode, and MR-RAPS, were utilized. Sensitivity analyses were conducted employing MR-Egger intercept test, Cochran's Q test, and leave-one-out analysis as quality control measures.

Results

The Mendelian randomization study conducted in a European population revealed a decreased risk of Graves' disease associated with Bacteroidaceae (Odds ratio (OR) [95% confidence interval (CI)]: 0.89 [0.89 ~ 0.90], adjusted P value: <0.001), Bacteroides (OR: [95% CI]: 0.555 [0.437 ~ 0.706], adjusted P value: <0.001), and Veillonella (OR [95% CI]: 0.632 [0.492 ~ 0.811], adjusted P value: 0.016). No significant evidence of heterogeneity, or horizontal pleiotropy was detected. Furthermore, the preliminary MR analysis identified 13 bacterial species including Eubacterium brachy group and Family XIII AD3011 group, exhibiting significant associations with Graves' disease onset, suggesting potential causal effects.

Conclusion

A causal relationship exists between gut microbiota and Graves' disease. Bacteroidaceae, Bacteroides, and Veillonella emerge as protective factors against Graves' disease development. Prospective probiotic supplementation may offer a novel avenue for adjunctive treatment in the management of Graves' disease in the future.

What if gastrointestinal complications in endurance athletes were gut injuries in response to a high consumption of ultra-processed foods? Please take care of your bugs if you want to improve endurance performance: a narrative review

To improve performance and recovery faster, athletes are advised to eat more often than usual and consume higher doses of simple carbohydrates, during and after exercise. Sports energetic supplements contain food additives, such as artificial sweeteners, emulsifiers, acidity regulators, preservatives, and salts, which could be harmful to the gut microbiota and impair the intestinal barrier function. The intestinal barrier plays a critical function in bidirectionally regulation of the selective transfer of nutrients, water, and electrolytes, while preventing at the same time, the entrance of harmful substances (selective permeability). The gut microbiota helps to the host to regulate intestinal homeostasis through metabolic, protective, and immune functions. Globally, the gut health is essential to maintain systemic homeostasis in athletes, and to ensure proper digestion, metabolization, and substrate absorption. Gastrointestinal complaints are an important cause of underperformance and dropout during endurance events. These complications are directly related to the loss of gut equilibrium, mainly linked to microbiota dysbiosis and leaky gut. In summary, athletes must be cautious with the elevated intake of ultra-processed foods and specifically those contained on sports nutrition supplements. This review points out the specific nutritional interventions that should be implemented and/or discontinued depending on individual gut functionality.

COVID-19 as a trigger of Guillain-Barré syndrome: A review of the molecular mechanism

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a pandemic with serious complications. After coronavirus disease 2019 (COVID-19), several post-acute COVID-19 syndromes (PACSs) and long-COVID sequels were reported. PACSs involve many organs, including the nervous, gustatory, and immune systems. One of the PACSs after SARS-CoV-2 infection and vaccination is Guillain-Barré syndrome (GBS). The incidence rate of GBS after SARS-CoV-2 infection or vaccination is low. However, the high prevalence of COVID-19 and severe complications of GBS, for example, autonomic dysfunction and respiratory failure, highlight the importance of post-COVID-19 GBS. It is while patients with simultaneous COVID-19 and GBS seem to have higher admission rates to the intensive care unit, and demyelination is more aggressive in post-COVID-19 GBS patients. SARS-CoV-2 can trigger GBS via several pathways like direct neurotropism and neurovirulence, microvascular dysfunction and oxidative stress, immune system disruption, molecular mimicry, and autoantibody production. Although there are few molecular studies on the molecular and cellular mechanisms of GBS occurrence after SARS-CoV-2 infection and vaccination, we aimed to discuss the possible pathomechanism of post-COVID-19 GBS by gathering the most recent molecular evidence.

Role of gut microbiota in infectious and inflammatory diseases

Thousands of microorganisms compose the human gut microbiota, fighting pathogens in infectious diseases and inhibiting or inducing inflammation in different immunological contexts. The gut microbiome is a dynamic and complex ecosystem that helps in the proliferation, growth, and differentiation of epithelial and immune cells to maintain intestinal homeostasis. Disorders that cause alteration of this microbiota lead to an imbalance in the host’s immune regulation. Growing evidence supports that the gut microbial community is associated with the development and progression of different infectious and inflammatory diseases. Therefore, understanding the interaction between intestinal microbiota and the modulation of the host’s immune system is fundamental to understanding the mechanisms involved in different pathologies, as well as for the search of new treatments. Here we review the main gut bacteria capable of impacting the immune response in different pathologies and we discuss the mechanisms by which this interaction between the immune system and the microbiota can alter disease outcomes.

Effects of Microecological Regulators on Rheumatoid Arthritis: A Systematic Review and Meta-Analysis of Randomized, Controlled Trials

In this study, the available data from published randomized, controlled trials (RCTs) of the use of intestinal microecological regulators as adjuvant therapies to relieve the disease activity of rheumatoid arthritis (RA) are systematically compared. An English literature search was performed using PubMed, Embase, Scopus, Web of Science and the Cochrane Central Registry of Controlled Trials and supplemented by hand searching reference lists. Three independent reviewers screened and assessed the quality of the studies. Among the 2355 citations identified, 12 RCTs were included. All data were pooled using a mean difference (MD) with a 95% CI. The disease activity score (DAS) showed a significant improvement following microecological regulators treatment (MD (95% CI) of -1.01 (-1.81, -0.2)). A borderline significant reduction in the health assessment questionnaire (HAQ) scores was observed (MD (95% CI) of -0.11 (-0.21, -0.02)). We also confirmed the known effects of probiotics on inflammatory parameters such as the C-reactive protein (CRP) (MD -1.78 (95% CI -2.90, -0.66)) and L-1β (MD -7.26 (95% CI -13.03, -1.50)). No significant impact on visual analogue scale (VAS) of pain and erythrocyte sedimentation rate (ESR) reduction was observed. Intestinal microecological regulators supplementation could decrease RA activity with a significant effect on DAS28, HAQ and inflammatory cytokines. Nevertheless, these findings need further confirmation in large clinical studies with greater consideration of the confounding variables of age, disease duration, and individual medication regimens.

Encouraging Tactics with Genetically Modified Probiotics to Improve Immunity for the Prevention of Immune-Related Diseases including Cardio-Metabolic Disorders

The PI3K/AKT/mTOR signaling pathway may play crucial roles in the pathogenesis of obesity and diabetes mellitus, as well as metabolic syndromes, which could also be risk factors for cardio-metabolic disorders. Consistently, it has been shown that beneficial effects may be convoyed by the modulation of the PI3K/AKT/mTOR pathway against the development of these diseases. Importantly, the PI3K/AKT/mTOR signaling pathway can be modulated by probiotics. Probiotics have a variety of beneficial properties, with the potential of treating specific diseases such as immune-related diseases, which are valuable to human health. In addition, an increasing body of work in the literature emphasized the contribution of genetically modified probiotics. There now seems to be a turning point in the research of probiotics. A better understanding of the interactions between microbiota, lifestyle, and host factors such as genetics and/or epigenetics might lead to a novel therapeutic approach with probiotics for these diseases. This study might provide a theoretical reference for the development of genetically modified probiotics in health products and/or in functional foods for the treatment of cardio-metabolic disorders.

Stabilization of swine faecal samples influences taxonomic and functional results in microbiome analyses

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Stabilization of faecal samples improves the integrity of extracted DNA.

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Microbiome results are affected by sample stabilization.

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Results are similar for samples that were stabilized when frozen, to samples that were stabilized before freezing.

Studies on the microbiome of different species are on the rise, due to a growing interest in animal health and the safety of food products of animal origin. A challenge with studying animals’ microbiomes is to find methods that obtain a good representation of the microbial community of interest. Good unbiased sampling protocols are the basis for a solid experimental design, but may need to be done in environments where sample preservation could be difficult. In this study, we evaluate by shotgun sequencing the impact of stabilizing swine faeces samples using a commercial stabilizer (PERFORMAbiome • GUT | PB-200, DNA Genotek). Using stabilizer makes it possible to obtain DNA that is significantly less degraded than when the samples are not stabilized. Also, the results on the taxonomy and on the bacterial functions encoded in the microbiome are impacted by whether or not the samples are stabilized. Finally, the stabilization of samples that had already been frozen and stored at -80°C led to extraction and DNA quality results similar to those obtained from samples that were stabilized before freezing.

Genetics, Epigenetics, Cellular Immunology, and Gut Microbiota: Emerging Links With Graves' Disease

Graves’ disease (GD) is a well-known organ-specific autoimmune disease characterized by hyperthyroidism, goiter, and exophthalmos. The incidence of GD is approximately 2.0–3.0% in China and 0.5–2.0% in Western countries. Due to the complex pathogenesis and etiology of GD, current treatment methods have great side effects that seriously endanger human health. Therefore, it is particularly important to understand the pathogenesis of GD. Various studies have shown that genetics, epigenetics, cellular immunology, and gut microbiota are all involved in the development of GD. Genetically, CD25 gene and VDR gene polymorphisms are involved in the development of GD by increasing the ratio of Th17/Treg cells. Epigenetically, miR-23a-3p and lncRNA-MEG3 lead to Th17/Treg imbalance and participate in the progression of GD. Moreover, commensal microbe deletion can disrupt Th17/Treg balance and participate in the occurrence of GD. The imbalance of Th17/Treg cells induced by genetics, epigenetics, and gut microbiota plays a vital role in the pathogenesis of GD. Therefore, this article reviews the role of genetics, epigenetics, cellular immunology, and gut microbiota in the pathogenic mechanism of GD. This may lead to the development of novel therapeutic strategies and providing promising therapeutic targets.

Gut Microbiota as Regulators of Th17/Treg Balance in Patients With Myasthenia Gravis

Myasthenia gravis (MG) is an acquired neurological autoimmune disorder characterized by dysfunctional transmission at the neuromuscular junction, with its etiology associated with genetic and environmental factors. Anti-inflammatory regulatory T cells (Tregs) and pro-inflammatory T helper 17 (Th17) cells functionally antagonize each other, and the immune imbalance between them contributes to the pathogenesis of MG. Among the numerous factors influencing the balance of Th17/Treg cells, the gut microbiota have received attention from scholars. Gut microbial dysbiosis and altered microbial metabolites have been seen in patients with MG. Therefore, correcting Th17/Treg imbalances may be a novel therapeutic approach to MG by modifying the gut microbiota. In this review, we initially review the association between Treg/Th17 and the occurrence of MG and subsequently focus on recent findings on alterations of gut microbiota and microbial metabolites in patients with MG. We also explore the effects of gut microbiota on Th17/Treg balance in patients with MG, which may provide a new direction for the prevention and treatment of this disease.

Therapeutic potential of triptolide in autoimmune diseases and strategies to reduce its toxicity

With the increasing epidemiology of autoimmune disease worldwide, there is an urgent need for effective drugs with low cost in clinical treatment. Triptolide, the most potent bioactive compound from traditional Chinese herb Tripterygium Wilfordii Hook F, possesses immunosuppression and anti-inflammatory activity. It is a potential drug for the treatment of various autoimmune diseases, but its clinical application is still restricted due to severe toxicity. In this review, the pharmacodynamic effects and pharmacological mechanisms of triptolide in autoimmune diseases are summarized. Triptolide exerts therapeutic effect by regulating the function of immune cells and the expression of cytokines through inflammatory signaling pathways, as well as maintaining redox balance and gut microbiota homeostasis. Meanwhile, the research progress on toxicity of triptolide to liver, kidney, reproductive system, heart, spleen, lung and gastrointestinal tract has been systematically reviewed. In vivo experiments on different animals and clinical trials demonstrate the dose- and time- dependent toxicity of triptolide through different administration routes. Furthermore, we focus on the strategies to reduce toxicity of triptolide, including chemical structural modification, novel drug delivery systems, and combination pharmacotherapy. This review aims to reveal the potential therapeutic prospect and limitations of triptolide in treating autoimmune diseases, thus providing guiding suggestions for further study and promoting its clinical translation.

Appetite Suppression and Interleukin 17 Receptor Signaling Activation of Colonic Mycobiota Dysbiosis Induced by High Temperature and High Humidity Conditions

It is known that the microbiome affects human physiology, emotion, disease, growth, and development. Most humans exhibit reduced appetites under high temperature and high humidity (HTHH) conditions, and HTHH environments favor fungal growth. Therefore, we hypothesized that the colonic mycobiota may affect the host’s appetite under HTHH conditions. Changes in humidity are also associated with autoimmune diseases. In the current study mice were fed in an HTHH environment (32°C ± 2°C, relative humidity 95%) maintained via an artificial climate box for 8 hours per day for 21 days. Food intake, the colonic fungal microbiome, the feces metabolome, and appetite regulators were monitored. Components of the interleukin 17 pathway were also examined. In the experimental groups food intake and body weight were reduced, and the colonic mycobiota and fecal metabolome were substantially altered compared to control groups maintained at 25°C ± 2°C and relative humidity 65%. The appetite-related proteins LEPT and POMC were upregulated in the hypothalamus (p < 0.05), and NYP gene expression was downregulated (p < 0.05). The expression levels of PYY and O-linked β-N-acetylglucosamine were altered in colonic tissues (p < 0.05), and interleukin 17 expression was upregulated in the colon. There was a strong correlation between colonic fungus and sugar metabolism. In fimo some metabolites of cholesterol, tromethamine, and cadaverine were significantly increased. There was significant elevation of the characteristic fungi Solicoccozyma aeria, and associated appetite suppression and interleukin 17 receptor signaling activation in some susceptible hosts, and disturbance of gut bacteria and fungi. The results indicate that the gut mycobiota plays an important role in the hypothalamus endocrine system with respect to appetite regulation via the gut-brain axis, and also plays an indispensable role in the stability of the gut microbiome and immunity. The mechanisms involved in these associations require extensive further studies.

Bovine Immunology: Implications for Dairy Cattle

The growing world population (7.8 billion) exerts an increased pressure on the cattle industry amongst others. Intensification and expansion of milk and beef production inevitably leads to increased risk of infectious disease spread and exacerbation. This indicates that improved understanding of cattle immune function is needed to provide optimal tools to combat the existing and future pathogens and improve food security. While dairy and beef cattle production is easily the world's most important agricultural industry, there are few current comprehensive reviews of bovine immunobiology. High-yielding dairy cattle and their calves are more vulnerable to various diseases leading to shorter life expectancy and reduced environmental fitness. In this manuscript, we seek to fill this paucity of knowledge and provide an up-to-date overview of immune function in cattle emphasizing the unresolved challenges and most urgent needs in rearing dairy calves. We will also discuss how the combination of available preventative and treatment strategies and herd management practices can maintain optimal health in dairy cows during the transition (periparturient) period and in neonatal calves.

Mixture of probiotics reduces inflammatory biomarkers and improves the oxidative/nitrosative profile in people with rheumatoid arthritis

OBJECTIVES

Studies have demonstrated that the gut microbiota of people with rheumatoid arthritis (RA) is different from that of healthy individuals and could influence inflammation and oxidative stress. In this study, we sought to evaluate the effects of supplementation with a mixture of probiotics on cytokine plasma levels, inflammatory biomarkers, oxidative/nitrosative stress profile, and Disease Activity Score-28 in people with RA.

METHODS

A randomized and double-blind placebo-controlled study was carried out with 42 participants with RA divided into two groups-the probiotic group (n = 21), who over 60 d took a daily ingestion of probiotics in a sachet containing 109 CFU/g each of five freeze-dried strains: Lactobacillus acidophilus La-14, Lactobacillus casei Lc-11, Lactococcus lactis Ll-23, Bifidobacterium lactis Bl-04 and B. bifidum Bb-06; and the placebo group (n = 21) who over 60 d took a daily ingestion of maltodextrin.

RESULTS

The probiotic group showed a significant reduction in white blood cell count (P = 0.012) and tumor necrosis factor-α (P = 0.004) and interleukin 6 plasma levels (P = 0.039). However, no differences were observed in interleukin-10, adiponectin, C-reactive protein, erythrocyte sedimentation rate, ferritin, or Disease Activity Score-28 between the two groups. Regarding oxidative/nitrosative stress biomarkers, the probiotic group showed lower nitric oxide metabolites (P = 0.004) and higher sulfhydryl group (P = 0.028) and total radical-trapping antioxidant parameters (P = 0.019) than the placebo group. However, lipid hydroperoxide and protein carbonyl did not differ between groups (P > 0.05).

CONCLUSIONS

The mixture of probiotics reduced inflammatory biomarkers and improved the oxidative/nitrosative profile in people with RA.

Immune System, Microbiota, and Microbial Metabolites: The Unresolved Triad in Colorectal Cancer Microenvironment

Colorectal cancer (CRC) is one of the most common cancers worldwide. As with other cancers, CRC is a multifactorial disease due to the combined effect of genetic and environmental factors. Most cases are sporadic, but a small proportion is hereditary, estimated at around 5-10%. In both, the tumor interacts with heterogeneous cell populations, such as endothelial, stromal, and immune cells, secreting different signals (cytokines, chemokines or growth factors) to generate a favorable tumor microenvironment for cancer cell invasion and metastasis. There is ample evidence that inflammatory processes have a role in carcinogenesis and tumor progression in CCR. Different profiles of cell activation of the tumor microenvironment can promote pro or anti-tumor pathways; hence they are studied as a key target for the control of cancer progression. Additionally, the intestinal mucosa is in close contact with a microorganism community, including bacteria, bacteriophages, viruses, archaea, and fungi composing the gut microbiota. Aberrant composition of this microbiota, together with alteration in the diet-derived microbial metabolites content (such as butyrate and polyamines) and environmental compounds has been related to CRC. Some bacteria, such as pks+ Escherichia coli or Fusobacterium nucleatum, are involved in colorectal carcinogenesis through different pathomechanisms including the induction of genetic mutations in epithelial cells and modulation of tumor microenvironment. Epithelial and immune cells from intestinal mucosa have Pattern-recognition receptors and G-protein coupled receptors (receptor of butyrate), suggesting that their activation can be regulated by intestinal microbiota and metabolites. In this review, we discuss how dynamics in the gut microbiota, their metabolites, and tumor microenvironment interplays in sporadic and hereditary CRC, modulating tumor progression.

Dysbiosis From a Microbial and Host Perspective Relative to Oral Health and Disease

The significance of microbiology and immunology with regard to caries and periodontal disease gained substantial clinical or research consideration in the mid 1960's. This enhanced emphasis related to several simple but elegant experiments illustrating the relevance of bacteria to oral infections. Since that point, the understanding of oral diseases has become increasingly sophisticated and many of the original hypotheses related to disease causality have either been abandoned or amplified. The COVID pandemic has reminded us of the importance of history relative to infectious diseases and in the words of Churchill "those who fail to learn from history are condemned to repeat it." This review is designed to present an overview of broad general directions of research over the last 60 years in oral microbiology and immunology, reviewing significant contributions, indicating emerging foci of interest, and proposing future directions based on technical advances and new understandings. Our goal is to review this rich history (standard microbiology and immunology) and point to potential directions in the future (omics) that can lead to a better understanding of disease. Over the years, research scientists have moved from a position of downplaying the role of bacteria in oral disease to one implicating bacteria as true pathogens that cause disease. More recently it has been proposed that bacteria form the ecological first line of defense against "foreign" invaders and also serve to train the immune system as an acquired host defensive stimulus. While early immunological research was focused on immunological exposure as a modulator of disease, the "hygiene hypothesis," and now the "old friends hypothesis" suggest that the immune response could be trained by bacteria for long-term health. Advanced "omics" technologies are currently being used to address changes that occur in the host and the microbiome in oral disease. The "omics" methodologies have shaped the detection of quantifiable biomarkers to define human physiology and pathologies. In summary, this review will emphasize the role that commensals and pathobionts play in their interaction with the immune status of the host, with a prediction that current "omic" technologies will allow researchers to better understand disease in the future.

Primary and Acquired Resistance to Immunotherapy in Lung Cancer: Unveiling the Mechanisms Underlying of Immune Checkpoint Blockade Therapy

After several decades without maintained responses or long-term survival of patients with lung cancer, novel therapies have emerged as a hopeful milestone in this research field. The appearance of immunotherapy, especially immune checkpoint inhibitors, has improved both the overall survival and quality of life of patients, many of whom are diagnosed late when classical treatments are ineffective. Despite these unprecedented results, a high percentage of patients do not respond initially to treatment or relapse after a period of response. This is due to resistance mechanisms, which require understanding in order to prevent them and develop strategies to overcome them and increase the number of patients who can benefit from immunotherapy. This review highlights the current knowledge of the mechanisms and their involvement in resistance to immunotherapy in lung cancer, such as aberrations in tumor neoantigen burden, effector T-cell infiltration in the tumor microenvironment (TME), epigenetic modulation, the transcriptional signature, signaling pathways, T-cell exhaustion, and the microbiome. Further research dissecting intratumor and host heterogeneity is necessary to provide answers regarding the immunotherapy response and develop more effective treatments for lung cancer.

An ambient temperature collection and stabilization strategy for canine microbiota studies

Similar to humans, the fecal microbiome of dogs may be useful in diagnosing diseases or assessing dietary interventions. The accuracy and reproducibility of microbiome data depend on sample integrity, which can be affected by storage methods. Here, we evaluated the ability of a stabilization device to preserve canine fecal samples under various storage conditions simulating shipping in hot or cold climates. Microbiota data from unstabilized samples stored at room temperature (RT) and samples placed in PERFORMAbiome·GUT collection devices (PB-200) (DNA Genotek, Inc. Ottawa, Canada) and stored at RT, 37 °C, 50 °C, or undergoing repeated freeze-thaw cycles, were compared with freshly extracted samples. Alpha- and beta diversity indices were not affected in stabilized samples, regardless of storage temperature. Unstabilized samples stored at RT, however, had higher alpha diversity. Moreover, the relative abundance of dominant bacterial phyla (Firmicutes, Fusobacteria, Bacteriodetes, and Actinobacteria) and 24 genera were altered in unstabilized samples stored at RT, while microbiota abundance was not significantly changed in stabilized samples stored at RT. Our results suggest that storage method is important in microbiota studies and that the stabilization device may be useful in maintaining microbial profile integrity, especially for samples collected off-site and/or those undergoing temperature changes during shipment or storage.

Dietary Habits and Nutrition in Rheumatoid Arthritis: Can Diet Influence Disease Development and Clinical Manifestations?

Rheumatoid arthritis (RA) is a systemic, autoimmune disease characterized by joint involvement, with progressive cartilage and bone destruction. Genetic and environmental factors determine RA susceptibility. In recent years, an increasing number of studies suggested that diet has a central role in disease risk and progression. Several nutrients, such as polyunsaturated fatty acids, present anti-inflammatory and antioxidant properties, featuring a protective role for RA development, while others such as red meat and salt have a harmful effect. Gut microbiota alteration and body composition modifications are indirect mechanisms of how diet influences RA onset and progression. Possible protective effects of some dietary patterns and supplements, such as the Mediterranean Diet (MD), vitamin D and probiotics, could be a possible future adjunctive therapy to standard RA treatment. Therefore, a healthy lifestyle and nutrition have to be encouraged in patients with RA.

Capsulized faecal microbiota transplantation ameliorates post-weaning diarrhoea by modulating the gut microbiota in piglets

Early weaning-induced stress causes diarrhoea, thereby reducing the growth performance of piglets. Gut bacterial dysbiosis has emerged as a leading cause of post-weaning diarrhoea. The present study aimed to investigate the effect of capsulized faecal microbiota transplantation (FMT) on the gut bacterial community, immune response and gut barrier function of piglets. Thirty-two weaned barrows were randomly divided into two groups. The recipient group was inoculated orally with capsulized faecal microbiota of healthy Tibetan pigs during the whole period of the trial, while the control group was given an empty capsule. The feed-to-gain ratio, diarrhoea ratio, and histological damage score of recipient piglets were significantly decreased. FMT treatment significantly increased the colon length of piglets. Furthermore, the relative abundances of Firmicutes, Euryarchaeota, Tenericutes, Lactobacillus, and Methanobrevibacter in the colon of recipient piglets were increased, and the relative abundances of Campylobacter and Proteobacteria were significantly decreased compared with those in the control group. CD4⁺ lymphocytes and CD4⁺/CD8⁺ ratio in the peripheral blood of recipient piglets were significantly increased. FMT treatment increased the IL-4 and IL-10 levels and decreased the TNF-α and INF-γ levels in the colonic tissue of piglets. The recipient piglets’ mRNA expression of TLR2, TLR8, NF-κB, and iNOS was significantly regulated. In addition, FMT significantly enhanced the gene expression of ZO-1. Overall, treatment with capsulized FMT ameliorated diarrhoea in piglets, with significant effects on limiting colon inflammatory responses, downregulating the TLR signalling pathway and the gene expression of iNOS, and strengthening intestinal barrier function by modulating the constituents of the gut microbiota.

Effect of Triptolide on Dextran Sodium Sulfate-Induced Ulcerative Colitis and Gut Microbiota in Mice

Triptolide is beneficial for the treatment of ulcerative colitis (UC), which is closely related to the gut microbiota. However, whether the therapeutic effects of triptolide involve the regulation of the gut microbiota is still unclear. In the present study, animal models of UC mice induced by dextran sodium sulfate (DSS) were established, the changes of gut microbiota in mice were detected by high-throughput sequencing. The effects of triptolide on DSS-induced UC mouse and its gut microbiota were studied. As a result, we found that triptolide exerted anti-inflammatory and therapeutic effects on UC mice. Sequencing results for the gut microbiota showed that the composition of the gut microbiota from DSS group was disordered as compared with that from the control group, consistent with a decrease in the abundance of flora. Triptolide treatment accelerated the recovery of the population of the gut microbiota and significantly improved the microbial diversity. At the phylum level, the population of Bacteroidetes decreased and that of Firmicutes increased. At the genus level, Bacteroides and Lachnospiraceae counts decreased. Thus, triptolide could regulate the composition of the gut microbiota, accelerate the recovery of microbiota, and exert good therapeutic effects in UC mice. Our results also revealed that fecal transplantation from triptolide-treated mice could relieve UC. This study provides a reference for the rational use of triptolide for the treatment of UC.

Mucosal Immune System of Cattle: All Immune Responses Begin Here

This article discusses key concepts important for mucosal immunity. The mucosa is the largest immune organ of the body. The mucosal barrier (the tight junctions and the "kill zone") along with the mucosa epithelial cells maintaining an anti-inflammatory state are essential for the mucosal firewall. The microbiome (the microorganisms that are in the gastrointestinal, respiratory, and reproductive tract) is essential for immune development, homeostasis, immune response, and maximizing animal productivity. Mucosal vaccination provides an opportunity to protect animals from most infectious diseases because oral, gastrointestinal, respiratory, and reproductive mucosa are the main portals of entry for infectious disease.

Diet, Microbiota, and Gut Permeability-The Unknown Triad in Rheumatoid Arthritis

Growing experimental and clinical evidence suggests that a chronic inflammatory response induced by gut dysbiosis can critically contribute to the development of rheumatic diseases, including rheumatoid arthritis (RA). Of interest, an adherence to a Mediterranean diet has been linked to a reduction in mortality and morbidity in patients with inflammatory diseases. Diet and intestinal microbiota are modifying factors that may influence intestinal barrier strength, functional integrity, and permeability regulation. Intestinal microbiota may play a crucial role in RA pathogenesis, but up to now no solid data has clarified a mechanistic relationship between gut microbiota and the development of RA. Nonetheless, microbiota composition in subjects with RA differs from that of controls and this altered microbiome can be partially restored after prescribing disease modifying antirheumatic drugs. High levels of Prevotella copri and similar species are correlated with low levels of microbiota previously associated with immune regulating properties. In addition, some nutrients can alter intestinal permeability and thereby influence the immune response without a known impact on the microbiota. However, critical questions remain to be elucidated, such as the way microbiome fluctuates in relation to diet, and how disease activity may be influenced by changes in diet, microbiota or diet-intestinal microbiota equilibrium.

Microbial transglutaminase: A new potential player in celiac disease

Microbial transglutaminase is heavily used in the food processing industries to improve food qualities. Being a protein's glue, by cross-linking it creates neoepitope complexes that are immunogenic and potentially pathogenic in celiac disease. Despite low sequence identity, it imitates functionally its family member, the endogenous tissue transglutaminase, which is the autoantigen of celiac disease. The present comprehensive review highlights the enzyme characteristics, endogenous and exogenous intestinal sources, its cross-talks with gluten and gliadin, its immunogenicity and potential pathogenicity and risks for the gluten induced conditions. If substantiated, it might represent a new environmental inducer of celiac disease. The present findings might affect nutritional product labeling, processed food additive policies and consumer health education.

TGFβ Superfamily Members as Regulators of B Cell Development and Function-Implications for Autoimmunity

The TGFβ superfamily is composed of more than 33 growth and differentiation factors, including TGFβ1, β2, β3, BMPs, GDFs, nodal-related proteins, and activins. These members usually exert pleiotropic actions on several tissues and control multiple cellular processes, such as cell growth, cell survival, cell migration, cell fate specification, and differentiation, both during embryonic development and postnatal life. Although the effects of these factors on immune responses were elucidated long ago, most studies have been focused on the actions of TGFβs on T cells, as major regulators of adaptive immunity. In this review, we discuss new findings about the involvement of TGFβ superfamily members in the control of B cell development and function. Moreover, the potential contribution of TGFβ signaling to control B cell-mediated autoimmune diseases and its utility in the design of new therapies are also discussed.

Current Evidence in Delivery and Therapeutic Uses of Fecal Microbiota Transplantation in Human Diseases-Clostridium difficile Disease and Beyond

The use of fecal microbiota transplantation (FMT) was first described in China in the 4th century by Ge Hong when "yellow soup," a fecal slurry, was administered for the treatment of severe food poisoning and diarrhea, a practice that continued for centuries. Bedouin groups also consumed stools of their camels as a remedy for dysentery. FMT was also applied in veterinary medicine in Europe in the 16th century. Additional therapeutic use of human excretions was described in Europe in the 18th and 19th century and in World War II, when gut bacteria were administered to German soldiers suffering from dysentery in the North African campaign. More scientifically, Eismann, in 1958, utilized fecal transplantation via enema in 4 patients for the treatment of severe pseudomembranous colitis with success. Following this report a number of isolated cases were published describing the use of FMT by different delivery routes for the treatment of a variety of illnesses.

Connecting the immune system, systemic chronic inflammation and the gut microbiome: The role of sex

Unresolved low grade systemic inflammation represents the underlying pathological mechanism driving immune and metabolic pathways involved in autoimmune diseases (AID). Mechanistic studies in animal models of AID and observational studies in patients have found alterations in gut microbiota communities and their metabolites, suggesting a microbial contribution to the onset or progression of AID. The gut microbiota and its metabolites have been shown to influence immune functions and immune homeostasis both within the gut and systematically. Microbial derived-short chain fatty acid (SCFA) and bio-transformed bile acid (BA) have been shown to influence the immune system acting as ligands specific cell signaling receptors like GPRCs, TGR5 and FXR, or via epigenetic processes. Similarly, intestinal permeability (leaky gut) and bacterial translocation are important contributors to chronic systemic inflammation and, without repair of the intestinal barrier, might represent a continuous inflammatory stimulus capable of triggering autoimmune processes. Recent studies indicate gender-specific differences in immunity, with the gut microbiota shaping and being concomitantly shaped by the hormonal milieu governing differences between the sexes. A bi-directional cross-talk between microbiota and the endocrine system is emerging with bacteria being able to produce hormones (e.g. serotonin, dopamine and somatostatine), respond to host hormones (e.g. estrogens) and regulate host hormones' homeostasis (e.g by inhibiting gene prolactin transcription or converting glucocorticoids to androgens). We review herein how gut microbiota and its metabolites regulate immune function, intestinal permeability and possibly AID pathological processes. Further, we describe the dysbiosis within the gut microbiota observed in different AID and speculate how restoring gut microbiota composition and its regulatory metabolites by dietary intervention including prebiotics and probiotics could help in preventing or ameliorating AID. Finally, we suggest that, given consistent observations of microbiota dysbiosis associated with AID and the ability of SCFA and BA to regulate intestinal permeability and inflammation, further mechanistic studies, examining how dietary microbiota modulation can protect against AID, hold considerable potential to tackle increased incidence of AID at the population level.

Impact of gut microbiota on drug metabolism: an update for safe and effective use of drugs

The intestinal mucosa and liver have long been considered as the main sites of drug metabolism, and the contribution of gut microbiota to drug metabolism has been under-estimated. However, it is now generally accepted that the gut microbiota plays an important role in drug metabolism prior to drug absorption or during enterohepatic circulation via various microbial enzymatic reactions in the intestine. Moreover, some drugs are metabolized by gut microbiota to specific metabolite(s) that cannot be formed in the liver. More importantly, the metabolism of drugs by gut microbiota prior to absorption can alter the systemic bioavailability of certain drugs. Therefore, understanding drug metabolism by gut microbiota is critical for explaining changes in the pharmacokinetics of drugs, which may cause significant alterations in drug-induced pharmacodynamics and toxicities. In this review, we describe recent progress with regard to the role of metabolism by gut microbiota in some drug-induced alterations of either pharmacological or toxicological effects to emphasize the clinical importance of gut microbiota for safe and effective use of drugs.

The Role of High-Mobility Group Box-1 and Its Crosstalk with Microbiome in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, definitely disabling, and potentially severe autoimmune disease. Although an increasing number of patients are affected, a key treatment for all patients has not been discovered. High-mobility group box-1 (HMGB1) is a nuclear protein passively and actively released by almost all cell types after several stimuli. HMGB1 is involved in RA pathogenesis, but a convincing explanation about its role and possible modulation in RA is still lacking. Microbiome and its homeostasis are altered in patients with RA, and the microbiota restoration has been proposed to patients with RA. The purpose of the present review is to analyze the available evidences regarding HMGB1 and microbiome roles in RA and the possible implications of the crosstalk between the nuclear protein and microbiome in understanding and possibly treating patients affected by this harmful condition.

Gut Microbiome and Bone: to Build, Destroy, or Both?

PURPOSE OF REVIEW

The gut microbiota can be considered a hidden organ that plays essential roles in host homeostasis. Exploration of the effects of microbiota on bone has just begun. Complimentary studies using germ-free mice, antibiotic, and probiotic treatments reveal a complicated relationship between microbiota and bone. Here, we review recent reports addressing the effect of gut microbiota on bone health, discuss potential reasons for discrepant findings, and explore potential mechanisms for these effects.

RECENT FINDINGS

Manipulation of microbiota by colonization of germ-free mice, antibiotics, or probiotic supplementation significantly alters bone remodeling, bone development and growth, as well as bone mechanical strength. Different experimental models reveal context-dependent effects of gut microbiota on bone. By examining phenotypic effects, experimental context, and proposed mechanisms, revealed by recent reports, we hope to provide comprehensive and fresh insights into the many facets of microbiota and bone interactions.

Lactobacillus johnsonii N6.2 Modulates the Host Immune Responses: A Double-Blind, Randomized Trial in Healthy Adults

Lactobacillus johnsonii N6.2 mitigates the onset of type 1 diabetes (T1D) in biobreeding diabetes-prone rats, in part, through changes in kynurenine:tryptophan (K:T) ratios. The goal of this pilot study was to determine the safety, tolerance, and general immunological response of L. johnsonii N6.2 in healthy subjects. A double-blind, randomized clinical trial in 42 healthy individuals with no known risk factors for T1D was undertaken to evaluate subject responses to the consumption of L. johnsonii N6.2. Participants received 1 capsule/day containing 10⁸ colony-forming units of L. johnsonii N6.2 or placebo for 8 weeks. Comprehensive metabolic panel (CMP), leukocyte subpopulations by complete blood count (CBC) and flow cytometry, serum cytokines, and relevant metabolites in the indoleamine-2,3-dioxygenase pathway were assessed. L. johnsonii N6.2 survival and intestinal microbiota was analyzed. Daily and weekly questionnaires were assessed for potential effects of probiotic treatment on general wellness. The administration of L. johnsonii N6.2 did not modify the CMP or CBC of participants suggesting general safety. In fact, L. johnsonii N6.2 administration significantly decreased the occurrence of abdominal pain, indigestion, and cephalic syndromes. As predicted, increased serum tryptophan levels increased resulting in a decreased K:T ratio was observed in the L. johnsonii N6.2 group. Interestingly, immunophenotyping assays revealed that monocytes and natural killer cell numbers were increased significantly after washout (12 weeks). Moreover, an increase of circulating effector Th1 cells (CD45RO⁺CD183⁺CD196⁻) and cytotoxic CD8⁺ T cells subset was observed in the L. johnsonii N6.2 group. Consumption of L. johnsonii N6.2 is well tolerated in adult control subjects, demonstrates systemic impacts on innate and adaptive immune populations, and results in a decreased K:T ratio. These data provide support for the safety and feasibility of using L. johnsonii N6.2 in prevention trials in subjects at risk for T1D.

Trial registration: This trial was registered at http://clinicaltrials.gov as NCT02349360.

Microbiota in T-cell homeostasis and inflammatory diseases

The etiology of disease pathogenesis can be largely explained by genetic variations and several types of environmental factors. In genetically disease-susceptible individuals, subsequent environmental triggers may induce disease development. The human body is colonized by complex commensal microbes that have co-evolved with the host immune system. With the adaptation to modern lifestyles, its composition has changed depending on host genetics, changes in diet, overuse of antibiotics against infection and elimination of natural enemies through the strengthening of sanitation. In particular, commensal microbiota is necessary in the development, induction and function of T cells to maintain host immune homeostasis. Alterations in the compositional diversity and abundance levels of microbiota, known as dysbiosis, can trigger several types of autoimmune and inflammatory diseases through the imbalance of T-cell subpopulations, such as Th1, Th2, Th17 and Treg cells. Recently, emerging evidence has identified that dysbiosis is involved in the progression of rheumatoid arthritis, type 1 and 2 diabetic mellitus, and asthma, together with dysregulated T-cell subpopulations. In this review, we will focus on understanding the complicated microbiota-T-cell axis between homeostatic and pathogenic conditions and elucidate important insights for the development of novel targets for disease therapy.